This morning, NPR’s Christopher Joyce shed more light on the connection between earthquakes and underground fracking fluid wastewater wells. Scientists believe the underwater storage sites caused recent quakes in Ohio, as StateImpact covered earlier this week.
Now let’s say there’s a fault line in the Earth. If the water content around the fault is changed, the fault might slip. If the water gets into the fault itself, it can lubricate the fault and trigger a quake.
Hydraulic fracturing pumps a lot of water underground, where it’s used to crack the rock and liberate gas. This may cause tiny quakes, but fracking goes on for a day or two, and the quakes are small.
Recent quakes reported in Ohio and Arkansas are associated with waste-water wells, not fracking wells. The water first used in fracturing rock is retrieved and pumped into these waste wells, which take in lots of water. And at more than 9,000 feet deep, the water is under high pressure that can build up over months or years. It’s this pressure that can actually create earthquakes.
In the 1960s, a waste-water well in Colorado, at the Rocky Flats Arsenal, is believed to have been the trigger for a 4.8-magnitude quake.